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Integrated triple-collinear counter-terms for the nested soft-collinear subtraction scheme
http://repo.scoap3.org/record/32740
We obtain analytic results for integrated triple-collinear splitting functions that emerge as collinear counter-terms in the context of the nested soft-collinear subtraction scheme [1]. With these results, all integrated subtraction terms required for NNLO QCD computations within this scheme are known analytically. In addition to improving efficiency and numerical stability of practical computations, the availability of these results will contribute towards establishing a general NNLO QCD subtraction formula for generic hard scattering processes in hadron collisions, similar to Catani-Seymour and FKS subtractions at NLO.Delto, MaximilianMon, 27 May 2019 15:31:35 GMThttp://repo.scoap3.org/record/32740urn:ISSN:1029-8479Springer/SISSA2019-05-23Analytic results for color-singlet production at NNLO QCD with the nested soft-collinear subtraction scheme
http://repo.scoap3.org/record/32598
We present analytic formulas that describe the fully-differential production of color-singlet final states in qq¯ \documentclass[12pt]{minimal}
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\begin{document}$$q{\bar{q}}$$\end{document} and gg annihilation, including all the relevant partonic channels, through NNLO QCD. We work within the nested soft-collinear scheme, which allows the fully local subtraction of infrared divergences. We demonstrate analytic cancellation of soft and collinear poles and present formulas for the finite parts of all integrated subtraction terms. These results provide an important building block for calculating NNLO QCD corrections to arbitrary processes at hadron colliders within the nested soft-collinear subtraction scheme.Caola, FabrizioSun, 05 May 2019 12:01:16 GMThttp://repo.scoap3.org/record/325982019-5-5Bottom-quark effects in Higgs production at intermediate transverse momentum
http://repo.scoap3.org/record/27896
We provide a precise description of the Higgs boson transverse momentum distribution including top and bottom quark contributions, that is valid for transverse momenta in the range m b ≲ p ⊥ ≲ m t , where m b and m t are the bottom and top quark masses. This description is based on a combination of fixed next-to-leading order (NLO) results with next-to-next-to-leading logarithmic (NNLL) transverse momentum resummation. We show that ambiguities in the resummation procedure for the b -quark loops are of the same order as the related fixed-order uncertainties. We conclude that the current uncertainty in the top-bottom interference contribution to the Higgs transverse momentum spectrum is O 20 % $$ \mathcal{O}\left(20\%\right) $$ .Caola, FabrizioSun, 09 Sep 2018 09:39:16 GMThttp://repo.scoap3.org/record/27896urn:ISSN:1029-8479Springer/SISSA2018-09-07The double-soft integral for an arbitrary angle between hard radiators
http://repo.scoap3.org/record/27670
We consider the double-soft limit of a generic QCD process involving massless partons and integrate analytically the double-soft eikonal functions over the phase-space of soft partons (gluons or quarks) allowing for an arbitrary relative angle between the three-momenta of two hard massless radiators. This result provides one of the missing ingredients for a fully analytic formulation of the nested soft-collinear subtraction scheme described in Caola et al. (Eur Phys J C 77(4):248, 2017 ).Caola, FabrizioWed, 29 Aug 2018 10:13:44 GMThttp://repo.scoap3.org/record/27670urn:ISSN:1434-6052Springer/Società Italiana di Fisica2018-8-29Higgs bosons with large transverse momentum at the LHC
http://repo.scoap3.org/record/25403
We compute the next-to-leading order QCD corrections to the production of Higgs bosons with large transverse momentum p⊥≫2mt at the LHC. To accomplish this, we combine the two-loop amplitudes for processes gg→Hg , qg→Hq and qq¯→Hg , recently computed in the approximation of nearly massless top quarks, with the numerical calculation of the squared one-loop amplitudes for gg→Hgg , qg→Hqg and qq¯→Hgg processes. The latter computation is performed with OpenLoops . We find that the QCD corrections to the Higgs transverse momentum distribution at very high p⊥ are large but quite similar to the QCD corrections obtained for point-like Hgg coupling. Our result removes one of the largest sources of theoretical uncertainty in the description of high- p⊥ Higgs boson production and opens a way to use the high- p⊥ region to search for physics beyond the Standard Model.Kudashkin, KirillWed, 09 May 2018 13:40:08 GMThttp://repo.scoap3.org/record/25403urn:ISSN:0370-2693Elsevier2018-06-26NNLO QCD corrections to associated <math><mi>W</mi><mi>H</mi></math> production and <math><mi>H</mi><mo>→</mo><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> decay
http://repo.scoap3.org/record/25094
We present a computation of the next-to-next-to-leading-order (NNLO) QCD corrections to the production of a Higgs boson in association with a W boson at the LHC and the subsequent decay of the Higgs boson into a bb¯ pair, treating the b quarks as massless. We consider various kinematic distributions and find significant corrections to observables that resolve the Higgs decay products. We also find that a cut on the transverse momentum of the W boson, important for experimental analyses, may have a significant impact on kinematic distributions and radiative corrections. We show that some of these effects can be adequately described by simulating QCD radiation in Higgs boson decays to b quarks using parton showers. We also describe contributions to Higgs decay to a bb¯ pair that first appear at NNLO and that were not considered in previous fully differential computations. The calculation of NNLO QCD corrections to production and decay sub-processes is carried out within the nested soft-collinear subtraction scheme presented by some of us earlier this year. We demonstrate that this subtraction scheme performs very well, allowing a computation of the coefficient of the second-order QCD corrections at the level of a few per mill.Caola, FabrizioTue, 24 Apr 2018 06:46:43 GMThttp://repo.scoap3.org/record/25094urn:ISSN:2470-0029APS2018-04-23Higher order corrections to mixed QCD-EW contributions to Higgs boson production in gluon fusion
http://repo.scoap3.org/record/24488
We present an estimate of the next-to-leading-order (NLO) QCD corrections to mixed QCD-electroweak contributions to the Higgs boson production cross section in gluon fusion, combining the recently computed three-loop virtual corrections and the approximate treatment of real emission in the soft approximation. We find that the NLO QCD corrections to the mixed QCD-electroweak contributions are nearly identical to NLO QCD corrections to QCD Higgs production. Our result confirms an earlier estimate of these O(ααs2) effects by Anastasiou et al. [J. High Energy Phys. 04 (2009) 003] and provides further support for the factorization approximation of QCD and electroweak corrections.Bonetti, MarcoFri, 23 Mar 2018 01:16:07 GMThttp://repo.scoap3.org/record/24488urn:ISSN:2470-0029APS2018-03-22Two-loop amplitudes for processes gg → Hg, qg → Hq and q q ¯ → H g $$ \mathrm{q}\overline{\mathrm{q}}\to \mathrm{H}\mathrm{g} $$ at large Higgs transverse momentum
http://repo.scoap3.org/record/23969
We compute the two-loop QCD corrections to amplitudes for processes gg → Hg, qg → Hq and q q ¯ → H g $$ q\overline{q}\to Hg $$ in the limit when the Higgs transverse momentum is larger than the top quark mass, p ⊥ ≫ m t . These amplitudes are important ingredients for understanding higher-order QCD effects on Higgs transverse momentum distribution at large p ⊥ .Kudashkin, KirillMon, 26 Feb 2018 05:36:07 GMThttp://repo.scoap3.org/record/23969urn:ISSN:1029-8479Springer/SISSA2018-02-21Three-loop mixed QCD-electroweak corrections to Higgs boson gluon fusion
http://repo.scoap3.org/record/23548
We compute the contribution of three-loop mixed QCD-electroweak corrections (αS2α2) to the gg→H scattering amplitude. We employ the method of differential equations to compute the relevant integrals and express them in terms of Goncharov polylogarithms.Bonetti, MarcoTue, 06 Feb 2018 10:24:35 GMThttp://repo.scoap3.org/record/23548urn:ISSN:2470-0029APS2018-02-05Nested soft-collinear subtractions in NNLO QCD computations
http://repo.scoap3.org/record/19770
We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector where energies and angles of unresolved particles vanish in a correlated fashion is redundant and can be discarded. This simple observation allows us to formulate a transparent iterative subtraction procedure for double-real emission contributions, to demonstrate the cancellation of soft and collinear singularities in an explicit and (almost) process-independent way and to write the result of a NNLO calculation in terms of quantities that can be computed in four space-time dimensions. We illustrate this procedure explicitly in the simple case of O(αs2) gluonic corrections to the Drell–Yan process of qq¯ annihilation into a lepton pair. We show that this framework leads to fast and numerically stable computation of QCD corrections.Caola, FabrizioTue, 18 Apr 2017 12:45:15 GMThttp://repo.scoap3.org/record/19770urn:ISSN:1434-6052Springer/Società Italiana di Fisica2017-4-18Two-loop electroweak corrections to Higgs–gluon couplings to higher orders in the dimensional regularization parameter
http://repo.scoap3.org/record/18783
We compute the two-loop electroweak correction to the production of the Higgs boson in gluon fusion to higher orders in the dimensional-regularization parameter ε=(d−4)/2 . We employ the method of differential equations augmented by the choice of a canonical basis to compute the relevant integrals and express them in terms of Goncharov polylogarithms. Our calculation provides useful results for the computation of the NLO mixed QCD-electroweak corrections to gg→H and establishes the necessary framework towards the calculation of the missing three-loop virtual corrections.Bonetti, MarcoMon, 30 Jan 2017 15:30:49 GMThttp://repo.scoap3.org/record/18783urn:ISSN:0550-3213Elsevier2017-02-07Two-loop gg → Hg amplitude mediated by a nearly massless quark
http://repo.scoap3.org/record/17986
We analytically compute the two-loop scattering amplitude gg → Hg assuming that the mass of the quark, that mediates the ggH interaction, is vanishingly small. Our computation provides an important ingredient required to improve the theoretical description of the top-bottom interference effect in Higgs boson production in gluon fusion, and to elucidate its impact on the Higgs boson transverse momentum distribution.Melnikov, KirillMon, 21 Nov 2016 10:08:10 GMThttp://repo.scoap3.org/record/17986urn:ISSN:1029-8479Springer/SISSA2016-11-18QCD corrections to vector boson pair production in gluon fusion including interference effects with off-shell Higgs at the LHC
http://repo.scoap3.org/record/16519
We compute next-to-leading order (NLO) QCD corrections to the production of two massive electroweak bosons in gluon fusion. We consider both the prompt production process gg → V V and the production mediated by an exchange of an s -channel Higgs boson, gg → H ∗ → V V . We include final states with both on- and off-shell vector bosons with leptonic decays. The gluonic production of vector bosons is a loop-induced process, including both massless and massive quarks in the loop. For gg → ZZ production, we obtain the NLO QCD corrections to the massive loops through an expansion around the heavy top limit. This approximation is valid below the top production threshold, giving a broad range of invariant masses between the Higgs production and the top production thresholds in which our results are valid. We explore the NLO QCD effects in gg → ZZ focusing, in particular, on the interference between prompt and Higgs-mediated processes. We find that the QCD corrections to the interference are large and similar in size to the corrections to both the signal and the background processes. At the same time, we observe that corrections to the interference change rapidly with the four-lepton invariant mass in the region around the ZZ production threshold. We also study the interference effects in gg → W + W − production where, due to technical limitations, we only consider contributions of massless loops. We find that the QCD corrections to the interference in this case are somewhat larger than those for either the signal or the background.Caola, FabrizioThu, 21 Jul 2016 14:14:32 GMThttp://repo.scoap3.org/record/16519urn:ISSN:1029-8479Springer/SISSA2016-07-18On the light quark mass effects in Higgs boson production in gluon fusion
http://repo.scoap3.org/record/15814
Production of Higgs bosons at the LHC is affected by the contribution of light quarks, that mediate the gg → Hg transition. Although their impact is suppressed by small Yukawa couplings, it is enhanced by large logarithms of the ratio of the Higgs boson mass or its transverse momentum to light quark masses. We study the origin of this enhancement, focusing on the abelian corrections to gg → Hg amplitudes of the form C F α s ℒ 2 n $$ {\left({C}_F{\alpha}_s{\mathrm{\mathcal{L}}}^2\right)}^n $$ , where ℒ ∈ ln s / m b 2 , ln p ⊥ 2 / m b 2 $$ \mathrm{\mathcal{L}}\in \left\{ \ln \left(s/{m}_b^2\right),\kern0.5em \ln \left({p}_{\perp}^2/{m}_b^2\right)\right\} $$ . We show how these non-Sudakov double logarithmic terms can be resummed to all orders in the strong coupling constant. Interestingly, we find that the transverse momentum dependence of these corrections is very weak due to a peculiar cancellation between different logarithmic terms. Although the abelian part of QCD corrections is not expected to be dominant, it can be used to estimate missing higher-order corrections to light quark contributions to Higgs boson production at the LHC.Melnikov, KirillTue, 31 May 2016 15:22:01 GMThttp://repo.scoap3.org/record/15814urn:ISSN:1029-8479Springer/SISSA2016-05-30QCD corrections to W + W − production through gluon fusion
http://repo.scoap3.org/record/13622
We compute the next-to-leading order (NLO) QCD corrections to the gg→W+W−→l1+ν1l2−ν¯2 process, mediated by a massless quark loop, at the LHC. This process first contributes to the hadroproduction of W+W− at O(αs2) , but, nevertheless, has a sizable impact on the total production rate. We find that the NLO QCD corrections to the gg→W+W− process amount to O(50)% , and increase the NNLO QCD cross sections of pp→W+W− by approximately two percent, at both the 8 TeV and 13 TeV LHC. We also compute the NLO corrections to gluonic W+W− production within a fiducial volume used by the ATLAS Collaboration in their 8 TeV measurement of the W+W− production rate and find that the QCD corrections are significantly smaller than in the inclusive case. While the current experimental uncertainties are still too large to make these differences relevant, the observed strong dependence of perturbative corrections on kinematic cuts underscores that extrapolation from a fiducial measurement to the total cross section is an extremely delicate matter, and calls for the direct comparison of fiducial volume measurements with corresponding theoretical computations.Caola, FabrizioTue, 26 Jan 2016 15:04:25 GMThttp://repo.scoap3.org/record/13622urn:ISSN:0370-2693Elsevier2017-03-21Two-loop helicity amplitudes for the production of two off-shell electroweak bosons in gluon fusion
http://repo.scoap3.org/record/10772
We compute the part of the two-loop virtual amplitude for the process gg → V 1 V 2 → l 1 l ¯ 2 ′ l 2 l ¯ 2 ′ $$ gg\to {V}_1{V}_2\to \left({l}_1{\overline{l}}_2^{\prime}\right)\left({l}_2{\overline{l}}_2^{\prime}\right) $$ , where V 1,2 are arbitrary electroweak gauge bosons, that receives contributions from loops of massless quarks. Invariant masses of electroweak bosons are allowed to be different from each other. Our result provides an important ingredient for improving the description of gluon fusion contribution to the production of four-lepton final states at the LHC.Caola, FabrizioMon, 22 Jun 2015 18:09:52 GMThttp://repo.scoap3.org/record/10772urn:ISSN:1029-8479Springer/SISSA2015-06-18Production of two Z-bosons in gluon fusion in the heavy top quark approximation
http://repo.scoap3.org/record/9637
We compute QCD radiative corrections to the continuum production of a pair of Z -bosons in the annihilation of two gluons. We only consider the contribution of the top quark loops and we treat them assuming that mt is much larger than any other kinematic invariant in the problem. We estimate the QCD corrections to pp→ZZ using the first non-trivial term in the expansion in the inverse top quark mass and we compare them to QCD corrections of the signal process, pp→H→ZZ .Melnikov, KirillThu, 19 Mar 2015 15:42:32 GMThttp://repo.scoap3.org/record/9637urn:ISSN:0370-2693Elsevier2015-05-11Two-loop helicity amplitudes for the production of two off-shell electroweak bosons in quark-antiquark collisions
http://repo.scoap3.org/record/4739
Knowledge of two-loop QCD amplitudes for processes q q ′ → V 1 V 2 → l 1 l ¯ 1 ′ l 2 l ¯ 2 ′ $$ qq^{\prime}\to {V}_1{V}_2\to \left({l}_1{\overline{l}}_1^{\prime}\right)\left({l}_2{\overline{l}}_2^{\prime}\right) $$ is important for improving the theoretical description of four-lepton production in hadron collisions. In this paper we compute these helicity amplitudes for all intermediate vector bosons, V 1 V 2 = γ * γ * , W + W − , ZZ , W ± Z , W ± γ * , including off-shell effects and decays to leptons.Caola, FabrizioWed, 12 Nov 2014 06:48:30 GMThttp://repo.scoap3.org/record/4739urn:ISSN:1029-8479Springer/SISSA2014-11-10Non-planar master integrals for the production of two off-shell vector bosons in collisions of massless partons
http://repo.scoap3.org/record/3949
We present the calculation of all non-planar master integrals that are needed to describe production of two off-shell vector bosons in collisions of two massless partons through NNLO in perturbative QCD. The integrals are computed analytically using differential equations in external kinematic variables and expressed in terms of Goncharov polylogarithms. These results provide the last missing ingredient needed for the computation of two-loop amplitudes that describe the production of two gauge bosons with different invariant masses in hadron collisions.Fabrizio CaolaSun, 14 Sep 2014 06:55:05 GMThttp://repo.scoap3.org/record/3949urn:ISSN:1029-8479Springer/SISSA2014-09-08Virtual corrections to Higgs boson pair production in the large top quark mass limit
http://repo.scoap3.org/record/3919
We calculate the three-loop matching coefficient CHH , required for a consistent description of Higgs boson pair production in gluon fusion through next-to-next-to-leading order QCD in the heavy top quark approximation. We also compute the gg→HH amplitude in mt→∞ approximation in the full theory and show its consistency with an earlier computation in heavy-top effective theory.Grigo, JonathanMon, 08 Sep 2014 13:12:47 GMThttp://repo.scoap3.org/record/3919urn:ISSN:0550-3213Elsevier2014-11On the NNLO QCD corrections to single-top production at the LHC
http://repo.scoap3.org/record/3093
We present a fully-differential calculation of the NNLO QCD corrections to the t -channel mechanism for producing single top quarks at the LHC. We work in the structure function approximation, computing QCD corrections to the light- and heavy-quark lines separately and neglecting the dynamical cross-talk between the two. The neglected contribution, which appears at NNLO for the first time, is color-suppressed and is expected to be sub-dominant. Within this approximation, we find that, for the total cross section, NNLO QCD corrections are in the few percent range and, therefore, are comparable to NLO QCD corrections. We also find that the scale independence of the theoretical prediction for single-top production improves significantly once NNLO QCD corrections are included. Furthermore, we show how these results change if a cut on the transverse momentum of the top quark is applied and derive the NNLO QCD prediction for the ratio of single top and single anti-top production cross sections at the 8 TeV LHC.Brucherseifer, MathiasWed, 02 Jul 2014 13:19:16 GMThttp://repo.scoap3.org/record/3093urn:ISSN:0370-2693Elsevier2014-09-07Two-loop planar master integrals for the production of off-shell vector bosons in hadron collisions
http://repo.scoap3.org/record/2781
We describe the calculation of all planar master integrals that are needed for the computation of NNLO QCD corrections to the production of two off-shell vector bosons in hadron collisions. The most complicated representatives of integrals in this class are the two-loop four-point functions where two external lines are on the light-cone and two other external lines have different invariant masses. We compute these and other relevant integrals analytically using differential equations in external kinematic variables and express our results in terms of Goncharov polylogarithms. The case of two equal off-shellnesses, recently considered in ref. [1], appears as a particular case of our general solution.Henn, JohannesWed, 11 Jun 2014 05:15:03 GMThttp://repo.scoap3.org/record/2781urn:ISSN:1029-8479Springer/SISSA2014-05-21Two-loop planar master integrals for the production of off-shell vector bosons in hadron col
lisions
http://repo.scoap3.org/record/2664
We describe the calculation of all planar master integrals that are needed for the computati
on of NNLO QCD corrections to the production of two off-shell vector bosons in hadron collisions. The most complica
ted representatives of integrals in this class are the two-loop four-point functions where two external lines are o
n the light-cone and two other external lines have different invariant masses. We compute these and other relevant
integrals analytically using differential equations in external kinematic variables and express our results in term
s of Goncharov polylogarithms. The case of two equal off-shellnesses, recently considered in ref. [1], appears as a
pa
rticular case of our general solution.Johannes M. HennTue, 03 Jun 2014 09:10:33 GMThttp://repo.scoap3.org/record/2664urn:ISSN:1029-8479Springer/SISSA2014-05-21